Mobile phone technology offers a variety of opportunities for innovative approaches to health communication and intervention. These opportunities have been amplified by the emergence of next-generation smartphone devices that are capable of rich multimedia and sophisticated interactivity. Smartphone-based programs can be integrated seamlessly into a user's daily life and natural setting to deliver tailored healt messaging, interactive psychosocial activities, cognitive exercises, momentary assessments and much more. Few studies to date have evaluated strategies for leveraging smartphone applications to promote tobacco prevention and cessation, and very few examples of evidence-based tobacco control programs currently exist for this nearly ubiquitous technology platform. This 3-year Phase II STTR is proposed to enhance and evaluate a smartphone-based program, AppSPIRE, which provides tailored tobacco cessation and prevention training for adolescents and young adults. The intervention is based on an existing evidence-based computer-based program entitled ASPIRE, and is guided by the Transtheoretical Model of Change, Social Cognitive Theory, and Addiction Framework. The aims of this study are to enhance a prototype application that was found to be feasible, usable and acceptable in a Phase I study, and to evaluate the program for efficacy among 400 ethnically diverse students at a large urban community college system. The proposed research will build upon our extensive federally funded line of tobacco and youth projects utilizing behavioral theory and innovative computer technology. The application is based on the considerable experience gained in a number of highly promising tobacco projects conducted by our investigative team. This study will significantly advance our understanding of mobile phone technology-assisted tobacco control among young tobacco users. It will inform future work to investigate ways in which m-technology may be used for health communication and cancer prevention.